function showhide(id) {
var Content = document.getElementById('k' + id);
var Button = document.getElementById('pic' + id);

if (Content.style.display == 'none') {
  Content.style.display = 'block';
  Button.src = 'pic/minus.gif';
}
else {
  Content.style.display = 'none';
  Button.src = 'pic/plus.gif';
}
}